KR20130001125A - Pneumatic tire for running on rough terrain - Google Patents

Abstract

PURPOSE: A pneumatic tire for running on rough terrain is provided to maintain a traction performance when going straight and to improve turn performance. CONSTITUTION: A pneumatic tire for running on rough terrain(1) includes a tread portion(2) and multiple blocks(4) and a rotating direction(R) is specified. The tread portion includes a center area(Cr) which is the 1/6 area of a tread full width(TWe) whose center is a tire equator, a shoulder area(Sh) which is the 1/4 area of the tread full from a tread end(2t), and a middle area(Mi) which is an area between the center area and the shoulder area. The block includes a center block(6), a middle block(7), and a shoulder block(8). The center block, the middle block, and the shoulder block make a horizontal long form in which the length of a tire axis direction(L1) is longer than the length of a tire circumference direction.

Description

PNEUMATIC TIRE FOR RUNNING ON ROUGH TERRAIN}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pneumatic tire for unsteady running that can improve turning performance while maintaining traction performance when going straight.

For example, ATER (ALL TERRAIN VEHICLE) for the purpose of running in unsteady areas such as limbs and sludge is known. Since the ATV is not provided with a differential device mounted on a passenger car, the left and right tires rotate at the same rotational speed. Therefore, in such an ATV, at least one tire should be slid while turning while sliding the tire on at least one side with respect to the road surface.

In addition, a block pattern in which a block having an elongated shape is formed in the tread portion is provided in the tread portion mounted tire mounted on the ATV. Such a block can exhibit traction performance when going straight. Related technologies include:

Patent Document 1: Japanese Patent Laid-Open No. 1-148606

However, such a block has a problem that it is difficult to slide while smoothly slipping the tire in the ATV, because a large traction is generated for unsteady even when turning, and there is a problem that the turning performance cannot be sufficiently maintained.

The present invention has been made in view of the above facts, and the center block, the middle block, and the shoulder block are formed in a horizontally long shape in which the length of the tire axial direction is larger than the width of the tire circumferential direction, and the tread of each block Unsteady driving that can improve turning performance while maintaining traction performance when going straight based on limiting the angle to the tire axial direction of the front edge toward the first side of the rotational direction of the surface to a predetermined range. The main object is to provide a pneumatic tire for use.

The invention according to claim 1 of the present invention includes a tread portion including a plurality of blocks, wherein the rotation direction is specified, and the tread portion is a region of 1/6 of the tread development width centered on the equator of the tire. An in center region, a shoulder region which is a quarter of the tread development width from the tread end, and a middle region which is an region between the center region and the shoulder region, wherein the block is located in the center region in the center of the center; And a center block having a city center in the middle region, and a shoulder block having a city center in the shoulder region, wherein the center block, the middle block, and the shoulder block have a length in a tire axial direction. It forms a horizontally long shape larger than the width of the tire circumferential direction, and the angle with respect to the tire axial direction of the front edge toward the first side in the rotational direction of the tread surface of each block is Characterized by satisfying the equation group (1).

Crθ <Miθ <Shθ.. (One)

Here, the sign is as follows.

Crθ: Angle with respect to the tire axis of the leading edge of the center block

Miθ: angle with respect to the tire axis of the leading edge of the middle block

Shθ: Angle with respect to the tire axis of the leading edge of the shoulder block

In addition, the invention according to claim 2, wherein the front edges of the middle block and the shoulder block are inclined toward the rear attachment side in the rotational direction from the tire equator side toward the tread end side. It is a traveling pneumatic tire.

Moreover, the invention of Claim 3 is the fixed tire for pneumatic tires of Claim 1 or 2 whose said length of the said shoulder block is larger than the said length of the said center block and the said middle block.

In addition, in the invention according to claim 4, the tread portion includes a center block row provided with the center block spaced in the tire circumferential direction, a middle block row provided with the middle block spaced in the tire circumferential direction, and the shoulder block. The pneumatic tire for tire driving according to any one of claims 1 to 3, wherein a shoulder row of rows provided in the tire circumferential direction is provided.

In addition, the invention according to claim 5 is the flat tire traveling pneumatic tire according to any one of claims 1 to 4, wherein the block is formed with a recess in which the tread surface is recessed.

In addition, in the invention described in claim 6, in the angle Crθ of the center block, the angle Miθ of the middle block, and the angle Shθ of the shoulder block, the following formula (2) and the following formula ( It is a tire for pneumatic driving of any one of Claims 1-5 which satisfy | fills 3).

1.1 ≦ Miθ / Crθ ≦ 1.6... (2)

1.1≤Shθ / Miθ ≦ 1.6... (3)

In addition, in this specification, unless otherwise indicated, the dimension of each part of a tire is rim-assembled in the rim which is not shown in figure, and the natural state of the no load which filled the internal pressure of 30 kPa is disclosed, and unless otherwise mentioned, a tire angle The dimension of the part is determined as the value in this natural state.

The pneumatic tire for driving a tire of this invention is equipped with the some block in a tread part, and a rotation direction is designated. The tread portion includes a center region, which is an area 1/6 of the tread development width centered on the tire equator, a shoulder region that is an area of 1/4 of the tread development width from the tread end, and a middle region, which is an area between the center region and the shoulder region. It includes.

The block includes a center block having a city center in the center region, a middle block having a city center in the middle region, and a shoulder block having a city center in the shoulder region, wherein the length of the tire axial direction is greater than the width in the tire circumferential direction Long form.

Furthermore, the angle with respect to the tire axial direction of the front edge toward the first arrival side of the tread surface of the block satisfies the following expression (1).

Crθ <Miθ <Shθ.. (One)

Here, the sign is as follows.

Crθ: Angle with respect to the tire axis of the leading edge of the center block

Miθ: angle with respect to the tire axis of the leading edge of the middle block

Shθ: Angle with respect to the tire axis of the leading edge of the shoulder block

As a result, the center block having a small angle Crθ exhibits great traction when the ground pressure is relatively increased, thereby improving running performance.

In addition, when the ATV turns, the ground pressures of the middle block and the shoulder block increase, but the angles (Miθ and Shθ) of the leading edges of these blocks gradually increase, so that the traction during the swing decreases and tire slippage is reduced. It can accelerate | stimulate, it can slide smoothly, and also can improve the turning performance.

BRIEF DESCRIPTION OF THE DRAWINGS It is an exploded view of the tread part which shows the flat tire for tire driving of this embodiment.
2 is a sectional view taken along the line AA in Fig.
3 is an enlarged view of FIG. 1.
4 is an enlarged view of a middle block.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 and 2 show the tires for driving in the still-life (hereinafter, simply referred to as "tires") 1 of the present embodiment, which are intended for driving in unsteady areas such as limbs and sludge. VEHICLE) tires are exemplified.

In the tread portion 2 of the tire 1, a plurality of blocks 4 partitioned by the tread grooves 3 are sparsely disposed at intervals in the tire circumferential direction and the tire axial direction, and the rotation direction R This designated block pattern is formed.

Such a block pattern can, for example, increase the amount of erosion of the block 4 to the ground, thereby exhibiting traction performance. Further, since the tread grooves 3 separating the blocks 4 are formed in a wide width, clogging of mud or the like can be prevented.

The sparse arrangement of the block 4 is the total area S of the outer surface of the tread portion 2 (the total area of the outer surface of the tread portion 2 when it is assumed that all tread grooves 3 are filled). It is grasped by the land ratio SL / S which is the sum SL of the area of the tread surface 4S of the entire block 4 with respect to.

In addition, when the land ratio SL / S is excessively small, there is a fear that the traction performance in the hard to medium furnace cannot be sufficiently maintained. On the contrary, even if the land ratio SL / S is excessively large, the traction performance in the soft path may not be sufficiently maintained. In this respect, the land ratio SL / S is preferably in the range of 20% to 30%.

Further, the tread portion 2 of the present embodiment has a tread development width from the center region Cr and the tread end 2t, which are areas 1/6 of the tread development width TWe centered on the tire equator C. FIG. A shoulder region Sh, which is a quarter of TWe, and a middle region Mi, which is an area between the center region Cr and the shoulder region Sh, is included.

The block 4 includes a center block 6 having a city center 6c in the center region Cr, a middle block 7 having a city center 7c in the middle region Mi, and a shoulder region Sh. A shoulder block 8 having a city center 8c. Accordingly, the tread portion 2 includes a center block row 11 in which the center blocks 6 are spaced apart in the tire circumferential direction, and a middle block row 12 in which the middle blocks 7 are spaced apart in the tire circumferential direction. ) And a shoulder block row 13 in which the shoulder blocks 8 are spaced apart in the tire circumferential direction.

As shown in FIG. 2, the center block 6, the middle block 7, and the shoulder block 8 include a tread surface 4S and a groove of the tread groove 3 from the tread surface 4S. It is formed including the block wall surface 4W which extends radially inward to the bottom 3B and partitions the block contour. In addition, the block height H1 from the tread surface 4S of each block 6, 7 and 8 to the groove bottom 3B is set to about 12 mm-16 mm, for example.

In addition, the tread surface 4S of each block 6, 7 and 8 is enlarged in FIG. 3, and the front edge 4a toward the first side of the rotation direction R and the back side toward the rear side are shown. An edge 4b and a pair of side edges 4c and 4c extending between the front edge 4a and the rear edge 4b, the length L1 of the tire axial direction being the width of the tire circumferential direction ( It is longer than W1).

In addition, the length L1 is measured as the maximum length in the tire axial direction of each block 6, 7 and 8, and the width W1 is the tire circumferential direction between the front edge 4a and the rear edge 4b. It shall be measured by the maximum length of.

The center block 6 has a pair of center inclined portions 6A and 6A which are inclined and extended from the tire equator C to the rear end side of the rotation direction R toward the tread ends 2t and 2t on both sides.

The center inclined portions 6A and 6A have a straight line with each of the front edge 4a and the rear edge 4b inclined from the tire equator C toward the tread end 2t toward the rear end of the rotation direction R. The side edge 4c extends between the front edge 4a and the rear edge 4b in the tire circumferential direction. Thus, the center block 6 is formed in a substantially inverted V shape in plan view.

The middle block 7 has a front edge 4a and a rear edge 4b inclined from the tire equator C to the tread end 2t toward the rear end side of the rotation direction R and extend in a straight line, and the side edges ( 4c extends between the front edge 4a and the rear edge 4b in the tire circumferential direction. Accordingly, the middle block 7 extends inclined from the tire equator C side to the tread end 2t side toward the rear attachment side of the rotational direction R, and is formed in a substantially parallelogram shape in plan view.

In addition, the middle block 7 of this embodiment is enlarged in FIG. 4, and the tire axial direction outer side of the front edge 4a of the middle block 7, and the tire axial direction of the rear edge 4b. The notch 7n which cut | disconnected the inside in substantially horizontally long form is provided.

This notch 7n can bend the front edge 4a and the rear edge 4b in a step shape to increase the edge length thereof, and is useful for exerting a grip when going straight and turning. Preferably, the length L4b in the tire axial direction of the cutout 7n is, for example, 50% to 70% of the length L1b of the middle block 7, and the width W4b in the tire circumferential direction is middle. Preferably, for example, about 5% to 15% of the width W1b of the block 7.

In addition, it is preferable that the inner corner 7ni of the notch 7n is chamfered by an arc. This prevents concentration of distortion in the inner corner 7ni and prevents damage such as cracks.

As shown in FIG. 3, the shoulder block 8 is inclined from the tire equator C to the rear end side of the rotation direction R toward the tread end 2t from the tire equator C. As shown in FIG. It extends and extends linearly, and the side edge 4c extends between the front edge 4a and the rear edge 4b in the tire circumferential direction. As a result, the shoulder block 8 is inclined and stretched from the tire equator C side to the tread end 2t side in the rear attachment side of the rotation direction R in the same manner as the middle block 7, and is substantially parallelogram in plan view. Is formed.

And in this embodiment, the angle with respect to the tire axial direction of the said front edge 4a of each block 6, 7, and 8 satisfy | fills following formula (1).

Crθ <Miθ <Shθ.. (One)

Here, the sign is as follows.

Crθ: Angle with respect to the tire axis of the leading edge of the center block

Miθ: angle with respect to the tire axis of the leading edge of the middle block

Shθ: Angle with respect to the tire axis of the leading edge of the shoulder block

In addition, the said angles (Crθ, Miθ and Shθ) are respectively measured in the tread portion 2 on the left and right with respect to the tire equator C. Therefore, in the case of the center block 6 which covers the tire equator C, it is measured in each front edge 4a, 4a of each center inclination part 6A, 6A arrange | positioned at the left and right tread part 2, respectively. . In addition, when the front edge 4a is not formed in linear form, it is calculated | required by the weighted average angle weighted by the length of the tire axial direction of the front edge 4a.

In such a block pattern, when the ground pressure of the center block 6 goes relatively large, the center block 6 having a small angle Crθ exhibits a large traction, thereby improving running performance.

In addition, when the ATV is turning, the ground pressures of the middle block 7 and the shoulder block 8 increase, and the angles Miθ and Shθ of the front edge 4a of these blocks 7 and 8 gradually increase. Therefore, at the time of turning, the traction in these blocks 7 and 8 decreases, and the slip of the tire 1 can be promoted. Therefore, the tire 1 can slide smoothly, and also turning performance can be improved.

In order to effectively exhibit the above effects, the angle Crθ of the center block 6, the angle Miθ of the middle block 7, and the angle Shθ of the shoulder block 8 are represented by the following equation (2) And it is preferable to satisfy following formula (3).

1.1 ≦ Miθ / Crθ ≦ 1.6... (2)

1.1≤Shθ / Miθ ≦ 1.6... (3)

This makes it possible to gradually and gradually increase the angles (Crθ, Miθ and Shθ) smoothly from the center block 6 to the shoulder block 8, thereby achieving both high traction performance and turning performance in a high dimension. Can be.

If the ratio Miθ / Crθ is less than 1.1, the inclination of the leading edge 4a of the middle block 7 may not be sufficient, and the tire 1 may not slide smoothly. On the contrary, when the ratio Miθ / Crθ exceeds 1.6, there is a fear that the traction in the middle block 7 may be excessively lowered. From this point of view, the ratio (Miθ / Crθ) is more preferably 1.2 or more, and more preferably 1.5 or less.

From the same viewpoint, the ratio (Shθ / Miθ) is more preferably 1.2 or more, more preferably 1.5 or less.

In addition, the angle Crθ of the center block 6 is preferably 5 degrees to 12 degrees. If the angle Crθ exceeds 12 degrees, the traction may not be sufficiently exhibited. On the contrary, when the angle Crθ is less than 5 degrees, there is a fear that the traction cannot be sufficiently lowered at the time of turning initial stage.

Further, in order to balance the traction and the turning performance in the straight line, the ratio L1 / W1 of the length L1 and the width W1 of each of the blocks 6, 7 and 8 is 180% to 340. % Is preferred.

Moreover, when the said ratio L1 / W1 is less than 180%, block rigidity will become large too much and traction will be exhibited even when turning, and there exists a possibility that it may not fully improve turning performance. On the contrary, when the ratio L1 / W1 exceeds 340%, the block stiffness in the tire circumferential direction is excessively lowered, and there is a concern that traction cannot be sufficiently obtained. From this point of view, the ratio L1 / W1 is more preferably 200% or more, and more preferably 300% or less.

1, the ratio L1a / Wc of the length L1a of the tire axial direction of the center block 6, and the width Wc of the tire axial direction of the center area Cr is 60. % To 80% are preferred. If the ratio L1a / Wc is less than 60%, the traction may not be sufficiently obtained. On the contrary, when the ratio L1a / Wc exceeds 80%, there is a possibility that a large traction is exerted even during the turning and the turning performance cannot be sufficiently obtained. From this point of view, the ratio L1a / Wc is more preferably 65% or more, and still more preferably 75% or less.

Similarly, the ratio L1b / Wm of the tire axial length L1b of the middle block 7 and the width Wm of the tire axial direction of the middle region Mi is preferably 60% or more, more preferably. Preferably 65% or more is preferable, and also preferably 80% or less, more preferably 75% or less.

In addition, the ratio L1c / Ws of the length L1c in the tire axial direction of the shoulder block 8 and the width Ws (shown in FIG. 1) in the tire axial direction of the shoulder region Sh is preferably Is preferably at least 50%, more preferably at least 55%, more preferably at most 70%, more preferably at most 65%.

Moreover, it is preferable that the said length L1c of the shoulder block 8 is formed larger than each said length L1a, L1b of the center block 6 and the middle block 7. Thereby, the shoulder block 8 can increase the edge component of a tire axial direction, and can reduce rigidity of a tire circumferential direction. Therefore, the shoulder block 8 can reduce the traction by increasing the deformation amount of the block at the time of turning, and can make the tire 1 slip more smoothly. Preferably, the ratio L1c / L1a of the length L1c of the shoulder block 8 and the length L1a of the center block 6 is preferably 110% to 130%.

Moreover, when the said ratio L1c / L1a is less than 110%, there exists a possibility that the above effects cannot fully be improved. On the contrary, even if the said ratio L1c / L1a exceeds 130%, there exists a possibility that the deformation amount of the shoulder block 8 may become large too large at the time of turning, and it cannot fully maintain traction performance. From this point of view, the ratio (L1c / L1a) is more preferably 115% or more, and still more preferably 125% or less.

Moreover, it is preferable that the recessed part 4h which recessed the tread surface 4S is formed in each said block 6, 7, and 8. Such concave portions 4h can alleviate the rigidity of each of the blocks 6, 7, and 8 to enhance road followability to unsteady ground, and can further improve traction performance and turning performance when going straight.

In addition, the recessed part 4h of this embodiment keeps the width W2 (shown in FIG. 4) of a tire circumferential direction constant, and the width center line 6L, 7L of each block 6, 7, and 8, respectively. And 8L). Therefore, the recessed part 4h can make the block rigidity of each block 6, 7, and 8 substantially uniform over a tire axial direction, and can further improve the traction performance and turning performance at the time of going straight. Preferably, the width W2 of the recess 4h is about 15% to 35% of the width W1 of the block 4, and the length L2 in the tire axial direction (shown in FIG. 4) is the block. It is preferable that about 55% to 75% of the length L1 of (4) and about 70% to 85% of the depth D2 (shown in FIG. 2) of the block height H1.

Moreover, in each block 6, 7 and 8, as shown in FIG. 2, the side wall surface 4Ws and the tread surface 4S which extend to the groove bottom 3B from both sides of the tire axial direction of the tread surface 4S. It is preferable that the chamfered part 4t which cut | disconnected and cut | disconnected the corner of () by the inclined surface is formed. Such a chamfer 4t can reduce traction at the time of turning, and can smoothly slip the tire 1. Preferably, the angle θ3 with respect to the tread surface 4S of the chamfer 4t is about 30 to 60 degrees, and the ratio of the width W3 (shown in FIG. 3) to the length L1 of the block ( W3 / L1) is preferably about 5% to 10%.

In addition, each block 6, 7 and 8 has a corner of the front edge 4a and the side edge 4c, and a corner of the rear edge 4b and the side edge 4c, as shown in FIG. It is preferable that the chamfer 4u cut out by the inclined surface is formed. Such a chamfer 4u can also reduce traction at the time of turning.

As mentioned above, although especially preferable embodiment of this invention was described in detail, this invention is not limited to embodiment shown, It can change and implement in various embodiments.

<Examples>

The tires for driving on tireless driving having the basic structure of FIGS. 1 and 2 and having one block as the specifications of Table 1 were manufactured, and their performance was tested. In addition, the common specification is as follows.

Tire size:

Front wheel: AT21 × 7R10

Rear wheel: AT20 × 10R9

Rim Size:

Front wheels: 10 × 5.5AT

Rear wheels: 9 × 8.0AT

Land Ratio (SL / S): 20% to 30%

Width of center area (Wc): 57.1 mm

Middle zone width (Wm): 57.1 mm

Width of the shoulder area (Ws): 83.3 mm

block:

Block height (H1): 10 mm to 15 mm

Recess:

Width W2: 3mm to 5mm, Length L2: 20mm to 30mm, Depth D2: 5mm to 7mm

Chamfer:

Width W3a: 2 mm to 5 mm, Angle θ3a: 50 degrees

Cutout:

Length L4b: 20 mm to 25 mm, Width W4b: 1 mm to 3 mm

The test method is as follows.

Traction performance and turning performance when going straight

The tires provided for each test were rim-assembled on the rim, filled with internal pressure (front wheels: 27.5 kPa, rear wheels: 30 kPa), and mounted on the rear wheels of an ATV (rear drive sports type four-wheeled vehicle) with a displacement of 450 cc. The traction performance when moving around the course and the turning performance were evaluated by the 5-point method by the sensory evaluation. The larger the value, the better.

The test results are shown in Table 1.

As a result of the test, it was confirmed that the tire tire for driving in the embodiment can improve turning performance while maintaining traction performance when going straight.

One… Tires for flat driving 2... Tread portion
4… Block 6... Center block
7 ... Middle block 8... Shoulder block

Claims (6)

A pneumatic tire for driving on a tread having a plurality of blocks and having a rotational direction specified therein,
The tread portion is a center region, which is an area 1/6 of the tread development width centered on the tire equator, a shoulder region which is an area of 1/4 of the tread development width from the tread end, and an area between the center region and the shoulder region. Including a middle region,
The block includes a center block having a city center in the center region, a middle block having a city center in the middle region, and a shoulder block having a city center in the shoulder region,
The center block, the middle block, and the shoulder block form a horizontally long shape in which the length in the tire axial direction is larger than the width in the tire circumferential direction,
A tire for an unsteady running pneumatic tire, wherein an angle with respect to the tire axial direction of the front edge of the tread surface of each block toward the first arrival side of the block satisfies the following expression (1).
Crθ <Miθ <Shθ.. (One)
Here, the sign is as follows.
Crθ: Angle with respect to the tire axis of the leading edge of the center block
Miθ: angle with respect to the tire axis of the leading edge of the middle block
Shθ: Angle with respect to the tire axis of the leading edge of the shoulder block The tire tire for driving a tireless driving according to claim 1, wherein the front edges of the middle block and the shoulder block are inclined from the tire equator side to the tread end side in the rotational attaching side. The tire tire for driving a tire of claim 1 or 2, wherein the length of the shoulder block is larger than the length of the center block and the middle block. According to claim 1 or 2, The tread portion, the center block row provided with the center block is spaced in the circumferential direction of the tire, the middle block row provided with the middle block is spaced in the circumferential direction of the tire, and the shoulder The pneumatic tire for driving on which a block is provided with the shoulder block row provided in which the block spaced apart in the circumferential direction. The said tire block pneumatic tire of Claim 1 or 2 in which the said recessed part which recessed the tread surface is formed in the said block. The said angle Cr (theta) of the said center block, the said angle (Mi (theta)) of the said middle block, and the said angle (Sh (theta)) of the shoulder block are a following formula (2) and a following formula. (3) The tire for tire driving which is satisfied.
1.1 ≦ Miθ / Crθ ≦ 1.6... (2)
1.1≤Shθ / Miθ ≦ 1.6... (3)

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